PurposeThe analgesic efficacy of the Transversus Abdominis Plane (TAP) peripheral nerve block for postoperative pain control following abdominally-based breast reconstruction has never been studied in a randomized controlled trial (RCT).MethodsWe conducted a double-blinded, placebo-controlled RCT that followed a single-center, 1:1 allocation, two-arm parallel group superiority design in patients undergoing microsurgical abdominally-based breast reconstruction. Intraoperatively, bilateral multi-orifice epidural catheters were inserted under direct vision into TAP through a 3cm incision in the Triangle of Petit as previously described by our group. Postoperatively, patients were randomly assigned to receive intermittent boluses of a 0.2 mL/kg of 0.25% Bupivacaine (study group) or saline (placebo group) through the bilateral TAP catheters for the first 2 postoperative days (POD). In both groups, patients received intravenous hydromorphone through a patient-controlled analgesic (PCA) pump programmed for the demand-only mode set at 0.1mg/bolus every 5 minutes with no basal rate. Both the TAP catheters and PCA were discontinued on POD 3. The primary objective was to compare the mean total parenteral opioid consumption each postoperative day following surgery between the control and study groups in intravenous morphine equivalent units. The secondary outcome measures included total in-hospital cumulative opioid and anti-nausea consumption, daily patient-reported pain scores, nausea and sedation scores, Quality of Recovery score; time to ambulation, and duration of hospital stay. All results were analyzed using intention-to-treat.ResultsBetween September 2011 and June 2013, of the 155 patients assessed for eligibility, 18 were ineligible, 44 declined participation, and 93 patients enrolled into the trial and underwent randomization. Forty-nine patients received Bupivacaine (study arm) and 44 receive isotonic saline (control arm) in their TAP catheters postoperatively. 47/49 patients in the study group and 38/44 in the control group completed their primary outcome measurement. There were 11 postoperative complications (13%), 7 in the treatment group, 4 in the control group, and none was related to TAP catheter, and there were no flap failures. For the primary outcome, the reduction in parenteral morphine consumption was only significantly different between the two groups on POD 1. In the Bupivacaine group, the mean parenteral morphine consumption was 20.7 (SD=20.1) mg compared to 30.0(SD=19.1) mg in the placebo group (p=0.02) on POD 2. There were no differences between the two groups in any of the secondary outcomes measures.ConclusionsThis double-blinded, placebo-controlled RCT showed that the TAP block is a safe peripheral nerve block and provides a significant reduction in parenteral morphine consumption in the early postoperative period following abdominally-based microsurgical breast reconstruction.